Relevant to our research interests in animal models of neuropsychiatric diseases, our Laboratory of Behavioral Neuroscience collaborated with several molecular genetics laboratories on the behavioral phenotyping of transgenic and knockout mice with mutations in genes expressed in the brain. Over the past few years, we have developed and refined a multi-tiered strategy for mouse behavioral phenotyping. We have also developed new behavioral tasks for mice and adapted rat behavioral tasks for mice. Dr. Crawley began a new initiative last year to develop mouse behavioral tasks relevant to the symptoms of autism. Ultimately, these behavioral tasks will be used to identify genes that are uniquely expressed in strains of mice with social deficits. These experiments were conducted in collaboration with investigators at the University of North Carolina Chapel Hill, particularly Dr. Joseph Piven, Director of the Autism STAART project. Mouse behavioral genetics experiments were conceived to discover genes related to the social deficits that represent the fundamental symptoms of autism. Dr. Crawley and Dr. Sheryl Moy designed a three chambered automated apparatus that measures sociability and preference for social novelty in mice. George Dold and coworkers in the NIMH Research Services Branch built the prototype apparatus. Drs. Sheryl Moy and Jessica Nadler and technicians in the UNC Neurodevelopmental Disorders Research Center tested 20 inbred strains of mice on the social tasks. Social tendencies were scored consistently and quantitatively with the automated apparatus, when compared to human observer scoring. Robust social approach to a stranger mouse, and robust preference for a novel stranger mouse, were detected for most inbred strains, including C57BL/6J, DBA/2J, and FVB/NJ. Low social approach was detected in three strains, A/J, Balb/cJ, and BTBR T+tf/tf. Drs. Jessica Nadler, David Threadgill, and Terry Magnuson conducted DNA microarray analyses on five brain regions from the inbred strains. Dr. Fred Wright analyzed the statistical correlations between gene expression in each brain region for each strain. These experiments were designed to discover candidate genes in mice that may provide a new focus for human studies into the genetic basis of autism. A second approach toward identifying the genes mediating the core symptoms of autism was to evaluate the behaviors of lines of mice with experimentally targeted mutations in genes relevant to autism. Comprehensive behavioral phenotyping was conducted on each new line, consistent with our laboratory's multi-tiered strategy for behavioral phenotyping of transgenic and knockout mice. Dr. Crawley and Howard Hughes student intern Thomas Chen found normal social approach and social olfactory behaviors in oxytocin knockout mice generated by Dr. W. Scott Young, NIMH. Staff Scientist Joanna Hill, postbaccalaureates Katrina Cuasay and Maria Lim, and student volunteers Tabitha Morris and Madelaine Stone conducted the social behavior task and a range of developmental behavioral tasks on knockout mice deficient in vasoactive intestinal peptide, a developmental neuropeptide that has been implicated in autism. Dr. Jean Lauder bred and genotyped Fragile X mice for our behavioral phenotyping. Fragile X is a form of mental retardation in which a large proportion of patients also display the symptoms of autism. Dr. Moy discovered that Fragile X mutant mice showed some deficits in components of the automated social task. Behavioral analyses of several other mutant lines is in progress at NIMH and at the University of North Carolina. The goal of this research is to identify a mutant mouse model of autism with robust behavioral symptoms relevant to autism, that can be used to test mechanistic hypotheses and evaluate potential treatments for the symptoms of autism. Expanding on our search for genes mediating abnormal social behaviors, we continued a collaboration with Dr. Karen Berman, NIMH. Dr. Berman investigates Williams syndrome, a genetic disease with many physiological and behavioral symptoms, including hypersociability and visuospatial deficits. Dr. Berman, Dr. Alan Koretsky, and Dr. Crawley received an NIH Bench-to-Bedside Award to pursue human imaging and mouse behavioral phenotyping and imaging studies of Williams syndrome. Dr. Niels Galjart, Erasmus University, The Netherlands, kindly contributed breeding pairs of mice with mutations in Cyln2, a microtubule gene located within the region of chromosome 7 that is deleted in Williams syndrome. Dr. Crawley and Howard Hughes student Jordan Cohen tested Cyln2 -/-, +/-, and +/+ mice on the automated social task for social approach to a stranger mouse and social preference toward a novel stranger mouse. Lack of preference for social novelty was detected in the null mutants and heterozygotes, a behavioral phenotype that may be relevant to the indiscriminate approach behaviors in Williams Syndrome patients. These findings support a functional role for Cyln2 in the symptoms of Williams syndrome. Further, these experiments validate the usefulness of our social task in detecting extremes at both ends of the social spectrum. Task development will be critical to the success of modeling the symptoms of autism in mice. Visiting scientist Dr. Hewlet McFarlane, on sabbatical with us from Kenyon College in Ohio, tested juvenile play behaviors in mice. This stage of mouse social interactions may be analogous to social interactions during human ages 3-15, when impaired reciprocal social interactions are most clearly impaired in autistic patients. Dr. McFarlane also set up an automated system for measuring ultrasonic vocalizations in separated mouse pups. Contact quieting and maternal potentiation appear to encompass more cognitive and communicative components of mouse pup ultrasonic vocalizations. These vocalization tasks may be useful for modeling the social communication deficits in autistic patients, which usually begin at 1-3 years of age. Dr. McFarlane's experiments currently focus on a comparison of two inbred strains, C57BL/6J as a normal control, and BTBR T+tf/tf as a strain showing social approach deficits. At the University of North Carolina, Dr. Moy developed a hole board exploration task to measure perseverative behaviors relevant to the stereotyped, repetitive behaviors in autism. A comparison of C57BL/6J and BTBR T+tf/tf will be among the first experiments using the hole board task.